This IPCP-HTM application made in response to RFA Al-07-001 contains three Research Projects, one Scientific Core and an Administrative Core, under the direction of Principal Investigator, John P. Moore, PhD and co-Principal Investigator, Robin A. Shattock, PhD. The purpose of the program is to conduct in vitro and in vivo pre-clinical and animal model-based research intended to facilitate the development of a vaginal microbicide based on the use of inhibitors of HIV-1 entry, applied alone and/or in combination. Our goal is to use our collective knowledge of virology, immunology, formulation chemistry and mammalian biology to help develop a mechanism-based, HIV-1-specific microbicide(s). An emphasis will be the development and evaluation of long-lasting microbicide formulations and delivery methods, such as controlled release vaginal rings that can provide a continuous and constant supply of active compounds in situ for a period of weeks/months after the application of a single device, and semi-solid formulations that could be applied once-daily or even less frequently. The inhibitors that we will study include, but may not be limited to: the small molecule CCRs inhibitor, CMPDi67 (Merck);the small molecule attachment inhibitor BMS-C (Bristol-Myers Squibb);the small molecule CXCR4 inhibitor AMD3465 (AnorMED);the GP4i-based peptide fusion inhibitor, T-1249 (Trimeris). We propose: Research Project I: Robin Shattock, Characterization of entry inhibitors in human cervical and rectal tissue models, and in dendritic cells;Research Project II: Karl Malcolm, Practical Formulations of HIV-1 Entry Inhibitors;Research Project III: Ronald Veazey, Testing practical microbicides in macaques;Virology and Immunology Core: John P. Moore;Administrative Core: John P. Moore. Other senior members of the team include Melissa Robbiani and Mark Mitchnick (Particle Sciences, Inc) who will participate in Research Projects I and III, respectively, under Cooperative Agreements, and Steven Wolinsky who will take part in the Virology and Immunology Core, also under a Cooperative Agreement. The involvement of Particle Sciences fulfills the mandated corporate element of the proposed research program. If this application is successfully peer reviewed and approved for support by the NIH, the International Partnership for Microbicides will provide the majority of the funding required to support the research programs headed by Drs. Shattock, Robbiani and Wolinsky, as outlined in the Program Overview section of the application. PROJECT 1: Characterization of entry inhibitors in human cervical and rectal tissue models, and dendritic cells (PI Shattock, Robin J.) PROJECT 1 DESCRIPTION (provided by applicant): The potential role of microbicides in preventing the mucosal transmission of HIV-1 has been clearly identified. However, rigorous pre-clinical evaluation of candidate microbicides is essential to the selection of the best compounds for clinical trials, since this will, in the end, provide savings in costs and time, given the expense and length of formal efficacy trials. Concerns with performing efficacy trials with incompletely optimized microbicide candidates have been highlighted by recent failed or halted Phase III trials (COL-1492, SAVVY and Cellulose Sulfate);these trials have suggested that development and formulation of effective microbicides may not be as easy as first thought. While mononuclear cell cultures and animal models may provide important information for the evaluation of microbicides, anatomical, physiological and immunological issues suggest they may not adequately model events that occur in human mucosal tissue. Therefore a comprehensive program for pre-clinical development of microbicide candidates requires that information be accrued from several different model systems. Hence Dr. Shattock's and Robbiani's groups have developed in vitro models of the earliest events in HIV-1 infection of human mucosal tissue and dendritic cell driven HIV-1 spread. These models are ideally suited to test the efficacy of agents designed to block HIV-1 sexual transmission and have been widely used to evaluate potential microbicide candidates. Furthermore, experiments described here and cross validation with experiments described in project III, may identify potential biomarkers of efficacy, safety and compliance that could inform future clinical trials. In this project, we will use these established models to evaluate the efficacy and compatibility of HIV-1 entry inhibitors (alone and in combination) and their formulations. This research will be influenced and guided by work carried out within Core A, and will involve extensive interactions and collaborations with the scientists leading Research Projects II and III. The interactions between the different groups will result in the fast-tracking of the most promising inhibitor combinations and formulations for evaluation in the macaque model (Research Project III).